Genetic and structural characterization of H-2-controlled allelic forms of murine C4.

The patterns of expression of several types of genetic variation in murine C4 were investigated. Dominance was assessed for S-region-determined differences in molecular weight of the C4 alpha-chain from Sw7 strains relative to all other strains examined and in C4 hemolytic titers. Codominant expression in F1 hybrids was shown for both of the above variations. Comparison of tryptic peptide profiles of radiolabeled C4 beta-chains encoded by different S regions revealed differences in their primary structures. The demonstration of codominant expression for the variant C4 traits examined and the evidence from tryptic peptide maps for haplotype differences in C4 primary structure strongly support the hypothesis that polymorphism of murine C4 is controlled by structural genes which are located in the S region.